This invention relates to a new motion transmitting system useful in machinery and tooling, particularly, self-feeding drill and threading machines.
The art is replete with machine tools such as drill presses, tappers (for internal threading), and the like, which utilize the combination of rotary and linear motion of a cutting tool to remove material and shape a workpiece. In the past, linear movement of machine tool cutters was accomplished by a powered lead screw and gear transmission or in certain instances totally by hand. Usually, the machine operator positions the workpiece to a rotating tool and manually activates the power feed mechanism which automatically advances the tool into the workpiece. After completion of the cut, the operator disengages the power feed mechanism (or trip stops are set to accomplish this) and the tool is manually retracted from the workpiece to its starting point. This procedure is repeated until the workpiece is shaped to its finished specification.
In an attempt to improve drilling and tapping operations and adapt the process to high volume production, automatic tool advancement and retraction was introduced. Once started, the tool rapidly advances to a predetermined point; performs its work function; retracts to its original position; and shuts-off. These self-feeding drill and tapping machines generally consist of a spindle adapted to support a drill or tap which is powered rotationally by a pneumatic or electric motor and powered linearly to advance and retract by a pneumatic or hydraulic cylinder or by a rotating ball screw and stationary nut assembly. These machines require expensive power packs, fluid lines, fittings, control valves, filters, regulators, lubricators, and servo motors. In addition, they consist of many interacting parts, operate at limited spindle speeds, have inconsistent linear feed due to small bore cylinders, dissipate uncomfortable high frequency noise, and require regular rebuilding by trained maintenance personnel.
Moreover, the most accurate self-feeding tappers engage a lead screw and nut assembly with the same pitch as the workpiece to be threaded to ensure that each revolution of the spindle creates precise linear advancement of the tap. It is often found that thread cutting in various materials is impossible without the precise pitch control of lead screw tapping. However, these tappers are limited to a specific thread pitch unless they are disassembled and the desired lead screw and nut assembly interchanged, which is both time consuming and expensive.
It is, therefore, an object of the present invention to provide a new and improved motion transmitting system for self-feeding drill machines, tapping machines, and the like, which is simple, comprises few moving parts, is operable from one power source, has infinitely adjustable spindle speed, has positive, uniform, precisely controlled, linear feed, is portable, operated quietly, and requires low maintenance.
It is also an object of the present invention to provide a new and improved motion transmitting system for lead screw tapping machines wherein a single lead screw and nut assembly precisely cuts any thread pitch both unified national and metric.
It is a further object of the present invention to supply a new and improved motion transmitting system for self-feeding drill machines, tapping machines, and the like, which provides small machine shops with affordable, low cost automation.
The foregoing background and objects set forth a general view while other objects, features, and advantages will become apparent from the following description and drawings and by practice with the invention.